A large number of semiconductor devices that are electronic components are built in a wireless communication apparatus represented by a mobile phone. Semiconductor devices are required to suppress an adverse effect of electromagnetic waves to an interior and an exterior like a leakage of electromagnetic waves in order to prevent an adverse effect to communication characteristics. Hence, semiconductor devices which have a shielding function against the electromagnetic waves have been applied.
In general, a semiconductor device is formed by mounting a semiconductor chip on an interposer substrate that is an intermediate substrate to a mounting substrate, and by sealing this semiconductor chip by a resin. By providing a conductive electromagnetic-wave shielding film on the top face and the side face of this sealing resin, the semiconductor devices achieving the shielding function have been provided (see WO 2013/035819 A).
Such an electromagnetic-wave shielding film can be a laminate film of multiple kinds of metals. For example, an electromagnetic-wave shielding film is known which employs a laminated structure of forming a Cu film on an SUS film, and further forming an SUS film thereon.
In order to accomplish a sufficient shielding effect for an electromagnetic-wave shielding film, it is necessary to decrease the electric resistivity. Hence, the electromagnetic-wave shielding film needs to have a thickness to some level. In semiconductor devices, in general, when a film has a thickness of substantially 1 μm to 10 μm, an excellent shielding characteristic is expectable. In the case of the above electromagnetic-wave shielding film employing the laminated structure of SUS, Cu, and SUS, it is known that, when the thickness is substantially 1 to 5 μm, an excellent shielding effect is expectable.
As a forming method for the electromagnetic-wave shielding film, plating method is known. However, since the plating method needs wet processes such as a pre-process step, a plating process step, and a post-process step like wet-cleaning, those result in the increase of the manufacturing cost for a semiconductor device.
Accordingly, sputtering method that is a dry process is getting attention. A plasma processing apparatus that forms a film by plasma has been proposed as a film formation apparatus by sputtering method. The plasma processing apparatus introduces an inactive gas into a vacuum chamber in which a target is placed, and applies a DC voltage. The ions of the plasma inactive gas are caused to be collided with the target of the film formation material, and a film is formed by depositing the material beaten out from the target on a work-piece.
General plasma processing apparatuses are applied for a film formation with a thickness of 10 to several 100 nm that can be formed by a process time of several ten seconds to several minutes. However, as described above, it is necessary to form a film with a thickness in a micron order as the electromagnetic-wave shielding film. Since sputtering is a technology of forming a film by depositing particles of the film formation material on an object on which the film is formed, the thicker film thickness lengthens the time required to form a film.
Hence, in order to form the electromagnetic-wave shielding film, a processing time of substantially several ten minutes to an hour is necessary which is longer than general sputtering. In the case of, for example, the electromagnetic-wave shielding film employing the laminated structure of SUS, Cu, and SUS, a process time of around an hour is necessary in some cases to obtain a thickness of 5 μm.
In this case, according to sputtering method by plasma, a package that is an exterior component of a semiconductor device is continuously exposed to the plasma heat during the process time. Consequently, the package may be heated to a temperature around 200° C. until a film with a thickness of 5 μm is obtained.
In contrast, the heat resistant temperature of the package is substantially 200° C. in the case of a temporal heating of substantially several seconds to several ten seconds, but when the heating time exceeds several minutes, the heat resistant temperature is generally around 150° C. Hence, it is difficult to form the electromagnetic-wave shielding film in a micron order by general plasma sputtering method.
In order to address this technical disadvantage, plasma processing apparatuses may be provided with a cooling apparatus that suppresses a temperature rise of semiconductor packages. In this case, the apparatus structure becomes complex and large in size.
An objective of the present disclosure is to provide a film formation apparatus which employs a simple structure that is capable of suppressing heating of electronic components.